If you have trouble falling asleep and waking up sometimes, it may be because you're working against your body's natural circadian rhythms. The MEQ-SA (morningness-eveningness self-assessment) questionnaire is an old but still useful test to help you learn more about your internal clock.

Specifically, answering the 19-question quiz will tell you if you're an "evening type," "morning type," or "intermediate type." While you might already know if you're a real lark or a night owl, the questionnaire also can estimate when your brain starts producing melatonin to help you fall asleep easier and when your "natural" bedtime is.

The questionnaire is often used by medical professionals to help guide treatment for reducing insomnia, treating seasonal affective disorder (SAD), and reducing oversleeping in the morning.